example question

[hongnod]

When switch on "passphrase" as following.
flag.BoolVar(&passphrase, "passphrase", true, "ask for private key passphrase.")

it will output error message as following:
`E:\goph-1.2.1\examples\goph>gophex.exe
Enter Private Key Passphrase: panic: The handle is invalid.

goroutine 1 [running]:
main.askPass(0xb3ae66, 0x1e, 0x0, 0x0)
E:/goph-1.2.1/examples/goph/main.go:156 +0x1a5
main.getPassphrase(...)
E:/goph-1.2.1/examples/goph/main.go:168
main.main()
E:/goph-1.2.1/examples/goph/main.go:114 +0x4d7`
No chance to input Passphrase